Sydney train network brought to a standstill

Transport for NSW is advising passengers to consider alternative transport as peak hour approached.

"Trains on the Sydney rail network and intercity lines are stopped at platforms," Transport for NSW said in a statement shortly after 3.30pm.

"Crews are working to fix the issue as quickly as possible but there is no forecast.

"Passengers already travelling on the rail network are advised to listen to announcements and check information displays for service updates."